Process for the production of color-corrected color photographic images



g- 1, 1961 K. LOFFLER ETAL 2,994,607

PROCESS FOR THE PRODUCTION OF COLOR-CORRECTED COLOR PHOTOGRAPHIC IMAGES Filed Nov. 19, 1957 INVENTORS KARL LfiFFLER, WILL/BALD PELZ. OTTMAR WAHL.

ATTORNEYJ' United States Patent C PROCESS FOR THE PRODUCTION OF COL- OR-CORRECTED COLOR PHOTOGRAPHIC IMAGES Karl Liifller, Langenfeld, and Willibald Pelz and Ottmar Wahl, Opladen, Germany, assignors to Agfa Aktiengesellschaft, Leverkusen, Germany, a corporation of Germany Filed Nov. 19,1957, Ser. No. 697,403

Claims priority, application Germany Nov. 20, 1956 8 Claims. (Cl. 96-9) In the color photographic multi layer processes using color development, it is known that the three silver halide emulsion layers which are combined to form a photographic material and which are to carry the three partial color images are sensitive to blue, green or red light. Incorporated into the layers are color couplers which couple with the oxidation products of the color developer, suchas a primary aromatic amino. developer, during the color development, so that a yellow, a magenta and a cyan partial image are formed as well as silver images. These three partial color images form the complete color image after the silver and the residual silver halide are removed. It is known that these three component dyes do not conform to theoretical requirements as regards their light absorption and consequently cause incorrect control of the copying light during the copying process, thus leading to defects in the color reproduction. Attempts have been made to correct these defects by producing color masks for the transparent color negatives or color positives, which masks are to compensate for these defective absorptions and are thus to remove the incorrect control of the copying light. Numerous methods of producing such masks have been proposed, including those in which the residual color couplers remaining in the layers after completion of the color development are converted into dyestufis. The color couplers or components which are used in such multi-layer systems belong to various classes of compounds; thus, derivatives of aeeto-acetic acid or benzoyl acetic acid, such as for example benzoyl acetic acid amides, are used as yellow couplers, derivatives of pyrazolone, cyanacetophone, isoxazolone and oxythionaphthene are used as magenta couplers, and rerivativesot phenol or a-naphthol are usually used as cyan couplers.

With all these compounds, which react not only with the oxidation products of the color developer with formation of the image dyestufis, but also with diazonium compounds with formation of azo dyestufis, there was the possibility of the residual components remaining after the color development being converted into azo dyestuffs. In this way, a magenta image was formed for example in a silver halide layer with a magenta coupler incorporated in a diffusion-resisting manner and a yellow azo dyestutf image was formed with opposite gradation, i.e. a color mask by which the defective absorption of the magenta image dyestutf in the blue range of the spectrum could be compensated.

The use of such a mask requires not only that the gradation shall be opposite but particularly that it shall be possible to adapt this mask image to the magentacolored image as regards sensitivity and course of gradation throughout the entire exposure range.

A process has now been found for subsequently masking a color-developed multi-layer material which is very simple and ofiers several advantages: this process consists in that the color images are treated with a solution of an azide, preferably an aqueous solution, the azide reacting with the residual color component.

Azides suitable for carrying out the process are compounds of the general formula RN in which R=an aliphatic or cycloaliphatic radical, for example methyl, ethyl, propyl, butyl, cyclohexyl, allyl, -=an aromatic radical, for example phenyl or a substituted phenyl radical,

:an aralkyl radical, for example benzyl,

==a heterocyclic radical, for example 2-benzthiazolyl,

:an acyl radical, for example -CONH it being possible for one or both of the hydrogen atoms to be substituted by any desired organic radicals for example alkyl, such as methyl, ethyl, propyl, butyl; aryl, such as phenyl, tolyl; cycloalkyl, such as cycloheXyl; aralkyl, such as benzyl;

:a sulphonyl radical, for example of the general formula Z.SO in which Z is a substituted or unsubstituted alkyl, such as methyl, ethyl, butyl, allyl; substituted or unsubstituted aryl, for example phenyl, aralkyl, for example benzyl,; cycloalkyl, such as cyclohexyl, a heterocyclic radical or a radical of the formula in which R and R represent like or different substituents, for example the aforementioned alkyl, aryl, aralkyl, cycloalkyl radicals, or guanidyl radi cal, for example H2N.C- i.

As compared with the known processes of masking with diazonium salt baths, the process of the present invention offers the following advantages:

-(1) The azides do not form any colored compounds with the binder of the layers, and the gelatine, for example, remains completely clear and colorless.

(2) Under the conditions usual for the processing of photographic materials, the azides do not react with the color formers for the yellow partial image which are incorporated into the layer.

(3) On the other hand, the azides react readily with the residual components for the magenta-colored partial image, so that reliable adaptability of the mask to the magenta image is obtained.

This ready adaptability is based on the fact that in the reaction of the components with azides, azo dyestufis are also formed, but the reaction sequence is fundamentally different. If the residual component is reacted with diazonium salts, azo dyestuiis are formed in accordance with the following reaction:

1 mol component-kl mol RN=NX (component) N=N--R -i.e. 1 mol of azo dyestufi is formed for 1 mol of residual component. By working with an azide RN in accordance with the process of the present invention, symmetrical azo dyestuffs are then formed in accordance with the reaction diagram:

2 mols of component-H mol R--N (component) N=N (component) In other Words, only half the number of molecules of azo dyestuffs are formed.

In the first case, the color density of the yellow masking dye is usually much too high, which from a photographic point of view leads to considerable difiiculties, since the defective absorption of the image dyestutt" is over-compensated.

In the single figure of the accompanying drawing, the following sensitometric curves are illustrated:

1magenta gradation (measured behind a green filter) 2defective absorption of the magenta image dye (measured behind a blue filter) 3ideal masking image gradation as obtained by the process of the present invention (measured behind a bluefilter) 4actual masking gradation of the masking dye consisting of component+diazonium salt (measured behind a blue filter) It is seen from the figure that the opposite gradation of the color mask 4 is too steep, whereby new color defects are formed. The considerable density of the mask fogging also produces difliculties in filtering out the copy, since high cyan-magenta filter factors are produced. If an attempt is made to reduce the mask density by shortening the reaction time, in other words by shortening the bath treatment, the whole of the residual component is no longer converted into dyestuff and thus the ratio between reacted and unreacted residual component is no longer constant for all exposure values and the masking is defective.

In the reaction with an azide the masking density is also considerably smaller for the reaction of the whole of the residual component and corresponds to the curve 3.

Thus, the mask gradation conforms to theoretical requirements and consequently provides optimum color correction. Since the treatment in the masking bath can con .tinue as long as required without any danger of overmasking, the danger of color fluctuation is much smaller, whereas it is necessary to maintain narrow tolerances as regards time, temperature and concentration of the masking baths in the known masking processes.

In principle, all azides are suitable for forming the masking dye images. A requirement is that they should 'be sufficiently soluble and stable to allow them to be used in the form of photographic baths. Consequently, the azides which are most suitable are those which are soluble in water or in a mixture of water with organic solvents which are soluble in water, and have the best possible stability both in solid form and in solution. These conditions are met by a considerable number of azides, particularly by sulphonyl azides. Among these azides, those which are derived from aromatic sulphonic acids of which the aromatic radical carries sulphonic acid and/or carboxyl groups as substituents are particularly valuable because of their stability and solubility. The reactivity is generally in the range between the weakly acid and strongly alkaline.

The azides are preferably applied in the form of their solutions in water or a mixture of water with organic solvents which are soluble in water, such as aliphatic lower alcohols, acetone or other ketones, dioxane, tetrahydrofurane, glycolmonomethylether or other ethers, and amines such as triethanolamine. The pH value may vary between 5 and 12, it is preferably adjusted to 7.5 to 9.5. The concentration of the azide may vary within 5 wide limits and amounts preferably to 0.5 to 2.5%.

The azide masking baths are used after the color de- -velopment, for example subsequent to the rinsing which follows the color development, or after one of the subsequent baths which are usual in the processing of color photographic materials. It is advisable to use them after the bleaching and fixing of the images, because then it is readily possible to judge the images before the masking, and the masking itself can take place inthe light. It is only important that previously no change of the residual component shall have taken place which excludes .a reaction with azide. Such a change can for example be caused by bleaching baths which contain potassium ferricyanide as bleaching agent. The use of such baths can reduce the reactivity With azides by oxidation of the residual component. It is, therefore, very suitable to work with bleach-fixing baths according to German patent specification No. 866,605 in conjunction with the process of the present invention. This method has, moreover, the advantage that only three baths are necessary for the production of a colored color-corrected image, namely:

(1) Developer bath (2) Bleach-fixing bath (3 Masking bath Example 1 An exposed multi-layer color film, the blue-sensitive silver halide layer of which contains 4-stearoylamidobenzoylacetanilide-3,5'-dicarboxylic acid, the green-sensitive silver halide emulsion layer of which contains 1-'(4'-phenoXy-3-sulpho) -phenyl 3 heptadebyl-S-pyrazolone and the red-sensitive halide emulsion layer of which contains the 2- N -methyl N octadecylamino-5'-sulphoanilide of l-hydroxy-Z-naphthoic acid as color coupler, is processed as follows:

(1) Color development bath minutes 6 Water 1000 N ethyl-N-fl-hydroxyethyl-p-amiuoaniline sulphate a 5.5 Potassium carbonate g 75 Anhydrous sodium sulphite g 2 Potassium bromide g 2.2 (2) Bleach-fixing bath "minutes" 8 Water 7 cc 1000 Sodium salt of ethylene diamine tetra-acetic acid g 52 Anhydrous sodium carbonate g 48 Crystalline ferrichloride g 30 Anhydrous sodium sulphite g 10 Crystalline sodium thiosulphate g 200 (3) Masking bath minutes 3 Water cc 1000 Sodium carbo g 25 4-chloro-3-carboxyl-l-phenyl sulphonyl azide g 10 The film is thoroughly rinsed between the baths and after the masking bath. After this processing, the film contains a well adapted yellow masking image in the magenta image layer as well as the partial color image.

The 4-chloro-3-carboxyl-l-phenyl sulphonyl azide is prepared as follows: f

A solution of 3.65 g. of sodium azide in 25 cc. of water is slowly added to a solution of 13.7 g. of 2-chlorobenzoic acid-S-sulphochloride in 15 cc. of methanol together with 29 cc. of a 10% aqueous sodium hydroxide solution so as to keep the pH value of the reaction mixture at about 7. The reaction mixture is filtered over charcoal and acidified. The sulphonyl azide precipitates and is isolated by filtration. Melting point: 128-130 C.

Example 2 An exposed multi-layer color film, the blue-sensitive silver halide layer of which contains p-methoxy-benzoylaceto-(2-N-methyl-N-octadecylamino-S-sulpho) anilide, the green-sensitive silver halide layer of which contains 1-(3'-w-sulphomethyl phenyl)-3-stearyl-5-pyrazolone and 10 g. of methane sulphonyl azide,

200 cc. of methanol and Y 400 cc. of 5% sodium carbonate solution made up with water to 1 litre of solution. I

Thereafter, bleaching and fixing is carried out for 8 minutes with the bleach fixing bat-h as described in Example l. The film is thoroughly rinsed between the baths and following the treatment in the bleach fixing bath. After being processed, the film contains a yellow masking image in the magenta image layer.

The methane sulphonyl azide is prepared as follows: A solution of 12 g. of methane sulphonyl chloride in 20 cc. of acetone is slowly added to a solution of 10 g. of sodium azide in 100 cc. of water at 2530 C. The reaction mixture is allowed to stand for 14 hours. Thereafter, it is diluted with 300 cc. of water. The oil which separates is isolated by steam distillation.

Example 3 A multi-layer film built up as described in Example 1 but containing p-octadecenyl-succinylamino-w-cyanacetophenone as the magenta component instead of the one described in Example 1, is treated for 6 minutes after the bleaching and fixing operation in a masking bath having the following composition:

10 g. of dimethyl aminosulphonyl azide,

200 cc. of methanol and 200 cc. of 5% sodium carbonate solution made up with water to 1 litre of solution.

After processing, the film contains in the green-sensitive layer amagenta image and a yellow image which is negative thereto.

The dimethylamino-sulphonyl azide is prepared according to the process disclosed in Example 2 while replacing the methane sulphonylchloride by 14.5 g. of dimethylamino-sulphonylchloride.

Example 4 An exposed film as in Example 2, but with 1-(4- methoxy-3-sulpho) phenyl-3-heptadecyl-5-pyrazolone, is color-developed and bleached and fixed in the same way. A yellow mask is thereafter formed by treatment for 10 minutes in a bath (pH 8.4) of the following composition:

1 litre of water 20 cc. of 10% sodium carbonate solution and 5 g. of Z-azidobenzthiazole-S-sulphonic acid.

In this case, the magenta image is so masked that an equal quantity of blue is absorbed independently of the magenta density at any area of the image.

The 2-azidobenzthiazole-S-sulphonic acid is prepared as follows:

To a solution of 13.4 g. of the sodium salt of Z-hydrazino benzthiazole-S-sulphonic acid in 70 cc. of water, there are added 11 cc. of a 5 molar aqueous sodium nitrite solution. The solution obtained is added drop by drop at -3 C. into 30 cc. of N aqueous hydrochloric acid. The 2-azidobenzthiazole-S-sulphonic acid precipitates slowly. It is sucked ofi, washed with a little ice water and dried in the air.

Example 5 The process of Example 1 is repeated while using as a masking bath a 3% aqueous solution of guanylazidnitrate (Annalen 380, p. 135) in which the developed film is bathed after bleaching and fixing for 3 minutes. The film is then treated for 5 minutes in a aqueous solulution of sodium carbonate. There is obtained a yellow masking image in the layer containing the magenta partial image.

Example 6 The exposed and developed multi-layer material of Example 2 is bleached for 5 minutes in a bath of the following composition:

1000 cc. of water; 20 g. of KBr; 4.6 g. of Kgcl'goq;

35 g. of KAl(SO 2.5 g. of anhydrous sodium-acetate;

55 cc. of glacial acetic acid (pH value 3.1).

Thereafter, the material is fixed in a solution of 200 g. of Na 'S O in 1000 cc. of water and then treated for 9 minutes in a solution of 6 g. of 2-azidobenzthiazole-6-sulphonic acid and 3.5 g. of sodium carbonate in 1000 cc. of water (pH value 8.8). The Z-azidobenzthiazol-6sulphonic acid is prepared by the process disclosed in Example 6, while using instead of 2-azidobenzthiazole-5- sulphonic acid the same amount of 2-azidobenzthiazole- 6-sulphonic acid. The latter compound is obtained by slowly adding while stirring .20 g. of 2-hydrazinobenzthia zole to 45 cc. of oleum (20%), whereby solution takes place and pouring the solution after 10 minutes into ice water, sucking off the precipitate formed and washing the latter first with a little water and then with methanol.

What we claim is:

1. In the process for the production of a color corrected photographic magenta image in a silver halide emulsion layer containing a non-diffusing color coupler selected from the group consisting of a magenta pyrazolone- (5) and a magenta cyanacetophenone coupler, which coupler is reacted with the oxidation product of a primary aromatic amine developer to produce a magenta azomethine dyestuff image, and wherein the residual color coupler is transformed into a correcting dyestufi image, the improvement according to which said residual color coupler transformation is elfected by contacting the residual coupler with a stable aqueous solution of a stable organic azide that thereby reacts with the residual coupler to form a yellow dye image.

2. A process according to claim 1 in which the azide corresponds to the general formula RN wherein R is a 2-benzthiazolyl radical.

3. A process according to claim 1 in which the azide corresponds to the general formula RN wherein R is the guanidyl radical.

4. A process according to claim 1, wherein said silver halide emulsion layer is combined with two further silver halide emulsion layers one of which contains a non-diffusing color coupler capable of reacting with the oxidation product of a primary aromatic amino developer for the production of a yellow dyestufi image and the other layer contains a non-diffusing color coupler capable of reacting with the oxidation product of a primary aromatic amino developer for the production of a cyan dyestuif image by a color developing that forms the magenta image.

5. A process according to claim 1 in which the azide corresponds to the general formula RN wherein R is an acyl radical of the formula R wherein R stands for a monovalent organic radical.

6. A process according to claim 1, wherein the treatment with the organic azide is effected after color development but before bleaching.

7. A process according to claim 1, wherein the treatment with the organic azide is effected after fixing.

8. A process according to claim 1, wherein the azide is a sulphonyl azide.

References Cited in the file of this patent UNITED STATES PATENTS Jennings Mar. 31, 1953 Powers Oct. 5, 1954 

1. IN THE PROCESS FOR THE PRODUCTION OF A COLOR CORRECTED PHOTOGRAPHIC MAGENTA IMAGE IN A SILVER HALIDE EMULSION LAYER CONTAINING A NON-DIFFUSING COLOR COUPLER SELECTED FROM THE GROUP CONSISTING OF A MAGENTA PYRAZOLONE (5) AND A MAGENTA CYANACETOPHENONE COUPLER, WHICH COUPLER IS REACTED WITH THE OXIDIATION PRODUCT OF A PERIMARY AROMATIC AMINE DEVELOPER TO PRODUCE A MAGENTA AZOMETHINE DYESTUFF IMAGE, AND WHEREIN THE RESIDUAL COLOR COUPLER IS TRANSFORMED INTO A CORRECTING DYESTUFF IMAGE, THE IMPROVEMENT ACCORDING TO WHICH SAID RESIDUAL COLOR COUPLER TRANSFORMATION IS EFFECTED BY CONTACTING THE RESIDUAL COUPLER WITH A STABLE AQUEOUS SOLUTION OF A STABLE ORGANIC AZIDE THAT THEREBY REACTS WITH THE RESIDUAL COUPLER TO FORM A YELLOW DYE IMAGE. 